Before suggested an question and answer post dedicated to this, we do have other venues to explore first.

Community adds are a good way to get community to support external resources. and IMSLP are already advertised though this and we can and should add any resources we deem important and are good sources of theory for lessons and source material respectively. 

We can also set up a chat for this which may be a better first go at trying to see as how we as a community handle it.. Resource post require a _lot_ of maintenance and having a chat dedicated to it would be a good preface to how well we could take care of it.